It is often desirable to mix two or more fluids and to distribute the fluids over a horizontal cross-section in a fluids handling system. For example, in processing a reactant stream of liquid hydrocarbons and hydrogen-containing gas in a catalytic reactor, it is important that the hydrogen-containing gas and hydrocarbons are well mixed before they are introduced into a catalyst bed. It is also important that the mixture is distributed relatively evenly across the whole cross-section of surface of the catalyst bed, so that the full capacity of the catalyst can best be utilized. Proper mixing and distribution of the fluids are also important in preventing the occurrence of overly hot or cold areas within a catalyst bed and for preventing turbulence and abrasion of catalyst particles.
In prior art systems for mixing and distributing downwardly flowing liquids and gases, three separate means have been used to accomplish three critical functions. The three functions are: (1) liquid-gas mixing; (2) liquid-gas distribution over a wide horizontal cross-section in the system; and (3) means for supporting the typically heavy liquid-gas mixing equipment, distribution equipment and any catalyst or other particulate solids bed above the equipment.
In many presently used fluids mixing and distributing systems, a single, vertically elongated reactor vessel is employed. Internally, the vessel is divided into several catalyst bed spaces. Catalyst supporting systems, quench gas introduction systems, fluids mixing systems, and fluids distributing systems are located between the bed spaces. Generally, at the bottom of each catalyst bed space there is located a perforated plate or other fluid-permeable means for supporting the catalyst bed. The perforated plate is normally made of heavy steel, and is anchored to the wall of the vessel, and is typically partially supported by heavy cross beams extending entirely across the vessel. Conventionally, a conduit grid or similar means is located in a space below the catalyst supporting means for introducing hydrogen quench gas. Below the quench gas introduction equipment, which also may require supporting beams, are normally provided means for mixing downwardly flowing liquid hydrocarbons and hydrogen-rich gas and means for mixing quench gas with the downwardly flowing fluids. In some cases, distribution means is provided adjacent to, or below, the fluids mixing equipment in order to distribute the fluids horizontally over a downstream catalyst bed. This distribution equipment also normally requires supporting means such as cross-beams. Other than providing support for the upper catalyst bed and mixing and distributing equipment, crossbeams or other supporting means are extraneous to carrying out the mixing and distributing funtions.
Various specific reactor internals designs have been suggested which attempt both (a) to provide adequate mixing of gases and liquids and (b) to provide adequate horizontal distribution of liquid-gas mixtures over a downstream catalyst bed. Such devices have often been expensive and overly difficult to fabricate, install and maintain. In contrast, the apparatus of the present invention, operated according to the process of the present invention, provides efficient mixing of liquid and gas flowing downwardly in a shell and also provides efficient distribution of the mixed fluids across the entire horizontal cross-section of the flow path, and does so without the use of overly heavy, expensive and difficult-to-install reactor internals, such as are found in many prior art devices. Further, the apparatus of the present invention employs the same elements to carry out all three functions of (1) fluid mixing, (2) fluid distribution and (3) catalyst bed and equipment support.